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Sensors, small electrical motors and harnesses are increasingly important for the optimal operation of modern motor vehicles. The perfect definition of these components represents an unquestionable factor of competitive advantage for today’s motor vehicle manufacturers, allowing them to reach high levels of driveability and travel comfort, fuel consumption efficiency, reduced pollutants and greater control reliability and accuracy of modern powertrains.

Sensors and small motors are active parts needed for proper definition of blends, air control, and verification of the positions and of all physical parameters used to provide the necessary feedback to the engine and transmission control units, allowing them to carry out the necessary controls, while the harnesses make it possible for the control units, sensors and “actuators” to work well together, exchanging information while preventing any external phenomena from compromising the operation of the whole.

In a modern Powertrain system, inside the throttle bodies and in the actuators for swirl and/or tumble devices, sensors determine the opening angle of the throttles, while the electric motors accurately open and close them based on the needs and on the desired speed. In fuel rails and in air intake manifolds, sensors measure the pressure and temperature of the fluids. In the engine exhaust, sensors are used to measure the air/fuel percentage, while on the engine they measure rotation speed, vibrations, noise level, temperatures of cooling fluids and lubricants, etc.

Magneti Marelli Powertrain is at the vanguard in this area too, and it is leader in Europe in the extensive use of contactless angular and linear measuring devices in the automotive sector, constantly committed to identifying and developing innovative solutions that maximize measuring quality and functionality at the lowest possible cost.

One application that is worthy of mention in the area of transmissions is the heavy use of contactless sensors in newly-designed robotized gearboxes.

Engagement/selection sensor for the dual-clutch transmission

Today’s robotized gearbox solutions require an ever-increasing mechanotronic integration of the devices used to detect the physical parameters of the system (i.e., gear selection engagement actuator position, oil pressure etc.).

Magneti Marelli, one of the first companies in the world to industrialize full contactless sensors on the ETB (Electronic Throttle Body), has long adopted this type of technology for many applications.

In the area of robotized gearboxes, contactless sensors offer a particularly appreciated benefit as they eliminate particularly burdensome gaskets/seals in hydraulic applications with high temperatures.

The various contactless technologies currently available on the market (i.e. LVDT, Hall, Magneto Resistive) also allow the identification of suitable “design to cost” solutions in relation to the electrical and mechanical accuracy requirements typical of the specific application.

In short, the benefits of contactless sensors solutions applied to the robotized gearbox can be summarized as follows:

High mechatronic integration

Elimination of gaskets/seals

Direct measurement of the physical parameter engagement/selection actuator position

Specifically, the Hall 2D technology, which allows minimum overall dimensions of the sensible element in view of reduced magnet size, is used for the latest-generation DCT applications.

The engagement sensors are integrated in a single “sensors unit” incorporated in the kinematic box with dedicated geometry, and they include up to four Hall 2D effect linear sensors, together with two Hall revolutions sensors (needed to measure the speed of the gears), while the selection sensor is a single linear sensor with Hall 2D effect outside the kinematic box.

This solution has been used in both the latest-generation robotized gearboxes and in DCTs.